DESCRIPTION (Abstract of the application) There is compelling evidence that the prevalence of celiac disease in the general population in the United States is higher than is generally appreciated and that patients with the symptoms classically associated with celiac disease, primarily diarrhea and weight loss, form a relatively small portion of the total celiac population. Some patients with celiac disease have medical problems associated with the malabsorption of specific nutrients without having problems with diarrhea and weight loss. Celiac disease is associated with the malabsorption of calcium and vitamin D resulting in osteoporosis. Although the prevalence of osteoporosis in the population of patients with celiac disease is known to be increased compared to the prevalence in the general population, the contribution of celiac disease to osteoporosis in the general population and the prevalence of celiac disease in the population of patients with osteoporosis are unknown. The central hypotheses of this proposal are: 1. The prevalence of celiac disease in the population of patients with osteoporosis is significantly increased above that of the general population. 2. Management of osteoporotic patients with celiac disease would be facilitated by the diagnosis and treatment of their celiac disease. These two premises taken together would justify a public health recommendation for screening patients with osteoporosis with serological tests for celiac disease. We have the unique resource of a Bone Health Clinic with a database that includes more than 2,000 individuals with osteoporosis as well as an even larger number of patients with normal bone density. In addition, the Bone Health Clinic sees more than 750 new patients per year of which 50% have osteoporosis. We propose to use the resources of our Bone Health Clinic to test this hypothesis. We have two Specific Aims: 1. To define the prevalence of celiac disease in a population of patients with osteoporosis and to compare the prevalence in a case control group of individuals with normal bone mass indices. This Specific Aim will be pursued using patients from the Bone Health Clinic database that will already have been defined as having osteoporosis and new patients accrued to the Bone Health Clinic. If the prevalence of celiac disease in the osteoporotic population is high enough one could justify a public health recommendation that all patients with osteoporosis undergo serologic screening for celiac disease. Studies under this Specific Aim will also allow recommendation for which sequence of serologic tests is most likely to be helpful in identifying patients with osteoporosis who also have celiac disease. 2. To determine if there are any significant differences in the clinical histories, laboratory studies or response to therapy between the populations of newly diagnosed and previously untreated osteoporotic patients with and without celiac disease. Specific studies will include: a. We will compare the population of patients with osteoporosis and celiac disease with the population of patients with osteoporosis without celiac disease in terms of their clinical characteristics and biochemical parameters determined at the time of diagnosis. b. We will compare patients with osteoporosis and celiac disease with patients with osteoporosis without celiac disease in terms of their response to therapy. Patients with osteoporosis without celiac disease will receive calcium and vitamin D for one year, whereas patients with osteoporosis and celiac disease will receive calcium, vitamin D and a gluten-free diet for one year. At the end of the year of therapy, bone mass indices will be repeated and the response to the therapy of the two groups will be compared.